• Title/Summary/Keyword: Surface Scattering Models

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Verification of Surface Scattering Models and Inversion Algorithms with Measurements of Polarimetric Backscattering Coefficients of a Bare Soil Surface (토양 표면에서의 편파별 후방 산란 계수 측정을 통한 산란 모델과 Inversion 알고리즘의 검증)

  • Hong, Jin-Young;Jung, Seung-Gun;Oh, Yi-Sok
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.17 no.12 s.115
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    • pp.1172-1180
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    • 2006
  • The backscattering coefficients of a bare soil surface were measured using an R-band polarimetric scatterometer, which were used to verify the validities of scattering models and inversion algorithms. The soil moisture contents and the surface roughness parameters (the RMS height and correlation length) were also measured from the soil surface. The backscattering coefficients were obtained from several scattering models with these surface parameters, and the computation results were compared with the measured backscattering coefficients. The soil moisture contents of the surface were retrieved from the measured backscattering coefficients, and compared with the measured surface parameters. This paper shows how well the scattering models agree with the measurements, and also shows the inversion results.

Comparison of the Numerical, Theoretical, and Empirical Scattering Models for Randomly Rough Surfaces

  • Hong Jin-Young;Oh Yisok
    • Proceedings of the KSRS Conference
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    • 2005.10a
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    • pp.725-728
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    • 2005
  • The scattering problem of the randomly rough surface is examined by the method of moments(MoM), small perturbation method (SPM), integral equation method (IEM) and the semi-empirical polarimetic model. To apply the numerical technique of the MoM to microwave scattering from a rough surface, at first, many independent randomly rough surfaces with a rms height and a correlation length are generated with Gaussian random deviate. Then, an efficient Monte Carlo simulation technique is applied to estimate the scattering coefficients of the surfaces.

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High-Frequency Bistatic Scattering from a Corrugated Sediment Surface

  • Cho, Hong-Sang;La, Hyoung-Sul;Yoon, Kwan-Seob;Na, Jung-Yul;Kim, Bong-Chae
    • The Journal of the Acoustical Society of Korea
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    • v.25 no.2E
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    • pp.60-68
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    • 2006
  • High-frequency bistatic scattering measurements from a corrugated surface were made in an acoustic water tank. First the azimuthal scattering pattern was measured from an artificially corrugated surface which has varying impedance. The corrugated surface was installed both transverse to the direction of incident wave and longitudinal to the direction of incident wave. The angle between the corrugated surface and the direction of the incident wave was about $45^{\circ}$. Second, the scattering strengths were measured from the flat sediment and the corrugated sediment. A critical angle of about $37^{\circ}$ was calculated in the acoustic water tank. The measurements were made at three fixed grazing angles: $33^{\circ}$ (lower than critical angle), $37^{\circ}$ (critical angle), and $41^{\circ}$ (higher than critical angle). The scattering angle and the grazing angle are equal in each measurement. Frequencies were from 50 kHz to 100 kHz with an increment of 1 kHz. The corrugated sediment was made transverse to the direction of the incident wave. The first measurement indicates that the scattering patterns depend on the relations between the corrugated surface and the direction of the incident wave. In the second measurement, the data measured from the flat sediment were compared to the APL-UW model and to the NRL model. The NRL model's output shows more favorable comparisons than the APL-UW model. In case of the corrugated sediment, the model and the measured data are different because the models used an isotropic wave spectrum of sediment roughness in the scattering calculations. The isotropic wave spectrum consists of $w_2$ and ${\gamma}_2$. These constants derived from sediment names or bulk size. The model which used the constants didn't consider the effect of a corrugated surface. In order to consider a corrugated surface, the constants were varied in the APL-UW model.

3D Generalized Langevin Equation (GLE) Approach to Gas-Surface Energy Transfer : Model H + H → $H_2/Si(100)-(2*1)$

  • Youxiang Zhang;Park, Seung Cheol
    • Bulletin of the Korean Chemical Society
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    • v.21 no.11
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    • pp.1095-1100
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    • 2000
  • we have proposed a three-dimensional GLE approach to gas-surface reactive scattering, model H + H $${\rightarrow}$H_2/Si(100)-(2$ ${\times}$1) system, and the implementation of 3D GLE method on the hydrogen on silicon surface has been presented. The formalism and algori thm of the 3D GLE are worked properly in the reactive scattering system. The calculated normal mode frequencies of surface vibrations were almost identical to previous harmonic slab calculations. The reaction probabilities were calculated for two energies. The calculations show that a very large amount of energy is transferred in surface in low energy scattering. Three different types of reaction mechanisms has been observed, which can not be shown in flat and rigid surface models. Further work on the reaction mechanisms and calculations of the vibrational and rotation distributions of products is in progress. The results will be reported elsewhere soon.

Microwave Radar Backscatter Model of Multiyear Sea Ice

  • Kim, Young-Soo
    • Korean Journal of Remote Sensing
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    • v.4 no.1
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    • pp.1-16
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    • 1988
  • Multiyear ice is quite thick in general, and it needs to be distinguished from thinner types of ice because it represents a severe navigational hazard. Here, models are described for the radar backscatter from multiyear sea ice, based on simple scattering layers. Under cold conditions, the radiative transfer volume-scatter model can describe the backscattering from multiyear ice for frequencies higher than about X-band, while the surface scattering contribution has to be included for lower frequencies. A simple semi-empirical model is shown to be a good approximation to the radiative transfer model in describing the volume scattering from multiyear ice.

Measurements of Microwave Polarimetric Backscattering from a Wet Soil Surface and Comparison with a Semi-empirical Scattering Model

  • Oh, Yi-Sok
    • Proceedings of the KSRS Conference
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    • 1999.11a
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    • pp.154-157
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    • 1999
  • Microwave polarimetric backscattering from a wet soil surface had been measured using a Ku-band polarimetric scatterometer at the incidence angles ranging from 10$^{\circ}$ to 70$^{\circ}$ Since the accurate target parameters as well as the radar parameters are necessary for radar scattering modeling, a complete and accurate set of ground truth data were also collected, from which accurate measurements were made of the rms height, correlation length, and dielectric constant. The measured polarimetric backscattering coefficients (vv-, hh-, vh-, hv-polarizations) were compared with theoretical models and empirical models. A new semi-empirical model for microwave polarimetric radar backscattering from bare soil surfaces was developed using polarimetric radar measurements and the knowledge based on the theoretical and numerical solutions. The model was found to yield very good agreement with the backscattering measurements of this study.

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Surface-Engineered Graphene surface-enhanced Raman scattering Platform with Machine-learning Enabled Classification of Mixed Analytes

  • Jae Hee Cho;Garam Bae;Ki-Seok An
    • Journal of Sensor Science and Technology
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    • v.33 no.3
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    • pp.139-146
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    • 2024
  • Surface-enhanced Raman scattering (SERS) enables the detection of various types of π-conjugated biological and chemical molecules owing to its exceptional sensitivity in obtaining unique spectra, offering nondestructive classification capabilities for target analytes. Herein, we demonstrate an innovative strategy that provides significant machine learning (ML)-enabled predictive SERS platforms through surface-engineered graphene via complementary hybridization with Au nanoparticles (NPs). The hybridized Au NPs/graphene SERS platforms showed exceptional sensitivity (10-7 M) due to the collaborative strong correlation between the localized electromagnetic effect and the enhanced chemical bonding reactivity. The chemical and physical properties of the demonstrated SERS platform were systematically investigated using microscopy and spectroscopic analysis. Furthermore, an innovative strategy employing ML is proposed to predict various analytes based on a featured Raman spectral database. Using a customized data-preprocessing algorithm, the feature data for ML were extracted from the Raman peak characteristic information, such as intensity, position, and width, from the SERS spectrum data. Additionally, sophisticated evaluations of various types of ML classification models were conducted using k-fold cross-validation (k = 5), showing 99% prediction accuracy.

Application of sound scattering models to swimbladdered fish, red seabream (Chrysophys major)

  • Kang Donhyug;Hwang Doojin;Na Jungyul;Kim Suam
    • Proceedings of the Acoustical Society of Korea Conference
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    • spring
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    • pp.233-236
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    • 2000
  • The acoustical response of fish depends on size and physical structure na, most important, on the presence or absence of a swimbladder. Acoustic scattering models for swimbladdered fish represent a fish by an ideal pressure-release surface having the size and shape as the swimbladder. Target strength experiments of red seabream (Chrysophrys major) have been conducted using 38 (split-beam), 120 (split-beam) and 200kHz (dual-beam) frequencies. At each start of each experiment, the live fish are placed in the cage at the surface, then the cage is lowed to about $4{\cal}m$ depth where it remains during the measurements. To test the acoustic models, predictions of target strength based on swimbladder morphometries of 10 red seabream offish total length from $103{\cal}mm{\;}to{\;}349{\cal}mm$ ($3 <$TL/\lambda$ < 45)are compared with conventional target strength measurements on the same, shock-frozen immediately after caged experiments. X-ray was projected along dorsal aspect to know the morphological construction of swimbladder. and fish body. At high frequencies, Helmholtz-kirchhoff(HK) approximation would greatly enhance swimbladdered fish modeling. Sound scattering model [HK-ray approximation model] for comparison to experimental target strength data was used to model backscatter measurements from individual fish. The scattering data can be used in the inverse method along with multiple frequency sonar systems to investigate the adequacy of classification and identification of fish

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Direct Determination of Spectral Phonon-Surface Scattering Rate from Experimental Data on Spectral Phonon Mean Free Path Distribution (실험적 포논 평균자유행로 스펙트럼 분포를 이용한 포논 스펙트럼 포논-표면 산란율 모델)

  • Jin, Jae Sik
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.40 no.9
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    • pp.621-627
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    • 2016
  • In this study, we present a model that can be used to calculate the phonon-surface scattering rate directly from the experimental data on phonon mean free path (MFP) spectra of nanostructures. Using this model and the recently reported length-dependent thermal conductivity measurements on $Si_{0.9}Ge_{0.1}$ nanowires (NWs), we investigate the spectral reduced MFP distribution and the spectral phonon-surface scattering rate in the $Si_{0.9}Ge_{0.1}$ NWs. From the results, it is found that the phonon transport properties with the material and the phonon frequency dependency of the spectral phonon-surface scattering rate per unit length of the NW. The model presented in this study can be used for developing heat transfer analysis models of nanomaterials, and for determining the optimum design for tailoring the heat transfer characteristics of nanomaterials for future applications of phonon nanoengineering.

Calculations of the Single-Scattering Properties of Non-Spherical Ice Crystals: Toward Physically Consistent Cloud Microphysics and Radiation (비구형 빙정의 단일산란 특성 계산: 물리적으로 일관된 구름 미세물리와 복사를 향하여)

  • Um, Junshik;Jang, Seonghyeon;Kim, Jeonggyu;Park, Sungmin;Jung, Heejung;Han, Suji;Lee, Yunseo
    • Atmosphere
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    • v.31 no.1
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    • pp.113-141
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    • 2021
  • The impacts of ice clouds on the energy budget of the Earth and their representation in climate models have been identified as important and unsolved problems. Ice clouds consist almost exclusively of non-spherical ice crystals with various shapes and sizes. To determine the influences of ice clouds on solar and infrared radiation as required for remote sensing retrievals and numerical models, knowledge of scattering and microphysical properties of ice crystals is required. A conventional method for representing the radiative properties of ice clouds in satellite retrieval algorithms and numerical models is to combine measured microphysical properties of ice crystals from field campaigns and pre-calculated single-scattering libraries of different shapes and sizes of ice crystals, which depend heavily on microphysical and scattering properties of ice crystals. However, large discrepancies between theoretical calculations and observations of the radiative properties of ice clouds have been reported. Electron microscopy images of ice crystals grown in laboratories and captured by balloons show varying degrees of complex morphologies in sub-micron (e.g., surface roughness) and super-micron (e.g., inhomogeneous internal and external structures) scales that may cause these discrepancies. In this study, the current idealized models representing morphologies of ice crystals and the corresponding numerical methods (e.g., geometric optics, discrete dipole approximation, T-matrix, etc.) to calculate the single-scattering properties of ice crystals are reviewed. Current problems and difficulties in the calculations of the single-scattering properties of atmospheric ice crystals are addressed in terms of cloud microphysics. Future directions to develop physically consistent ice-crystal models are also discussed.